A sum of Rs. 13360 was borrowed at $${\text{8}}\frac{3}{4}$$ % per annum compound interest and paid back in two years in two equal annual installments. What was the amount of each installment ?
a) Rs. 5769
b) Rs. 7569
c) Rs. 7009
d) Rs. 7500

Answer: b
Explanation:
$$\eqalign{ & {\text{Rate of interest (r)}} \cr & {\text{ = 8}}\frac{3}{4}\% = \frac{7}{{80}} = \frac{{87 \to {\text{ Installment}}}}{{80 \to {\text{Principal}}}} \cr} $$

⇒	I	80×87	→	87×87	……(i)
⇒	II	6400	→	7569	……(ii)

Since, installment is equal hence multiply equation (i) by 87
Total principal = 6960 + 6400 = 13360
13360 units = Rs. 13360
1 units = Rs. 1
7569 units = Rs. 7569
Each installment = Rs. 7569